Creating a permanent structure with high spatial resolution

ABSTRACT

In a method of creating a permanent structure with high spatial resolution, a substance which may be modified by an optical signal is provided in a writing area. The optical signal is applied to the writing area in such a way that a spatially limited partial area of the writing area is purposefully omitted, the spatially limited partial area being a local intensity minimum of the optical signal, and the optical signal, outside of the spatially limited partial area, being applied to the writing area in such a way that saturation is achieved in modifying the substance with the optical signal. Then, different states of the substance in the spatially limited partial area and of the substance in the partial areas of the writing area covered by the optical signal are permanently adjusted.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International ApplicationPCT/EP2004/003768 with an International Filing Date of Apr. 8, 2004 andclaiming priority to co-pending German Patent Application No. 103 17613.6 entitled “Räumlich hochauflösendes Abbilden und Modifizieren vonStrukturen”, filed on Apr. 13, 2003, to co-pending U.S. patentapplication Ser. No. 10/420,896 entitled “High spatial ResolutionImaging and Modification of Structures”, filed on Apr. 22, 2003, and toco-pending German Patent Application No. 103 25 459.5 entitled “Räumlichhochaufgelöstes Erzeugen einer dauerhaften Struktur”, filed on Jun. 5,2003.

This application is a continuation-in-part of the aforesaid U.S.application Ser. No. 10/420,896 entitled “High spatial ResolutionImaging and Modification of Structures”, filed on Apr. 22, 2003 now U.S.Pat. No. 7,064,824.

FIELD OF THE INVENTION

This invention relates to a method of creating a permanent structurewith high spatial resolution by using an optical signal. Particularly,the invention relates to method of creating a permanent structure withhigh spatial resolution, the method comprising the steps of providing asubstance, which may be modified by an optical signal, in a writingarea; of applying the optical signal to the writing area in such a waythat a spatially limited partial area of the writing area ispurposefully omitted; and of permanently adjusting different states ofthe substance in the spatially limited partial area and in the partialareas of the writing area covered by the optical signal. Further, theinvention relates to an apparatus having a writing area adapted to bepermanently modified by means of an optical signal. Particularly, theinvention can be applied in writing into an optical data storage and information of microlithographic structures.

The permanence of the structure created by the new method or with thenew apparatus shall be given for a period of time which is at least muchlonger than one minute and which is preferably much longer than one day;even more preferably the created structure remains up to a point in timeat which it is purposefully amended or deleted, so that the structurecan also be used during a very long interval of time after its creation.

DESCRIPTION OF RELATED ART

In a known method of creating a permanent structure with high spatialresolution by using an optical signal, in which an apparatus having awriting area adapted to be permanently structured by means of an opticalsignal is used, a coating of photoresist is exposed to an optical signaleverywhere where the coating of photoresist is to be permanentlymodified. Here, the desired structure does not consist of the modifiedpartial areas of the writing area but of partial areas purposefullyomitted with the optical signal.

The spatial resolution both of imaging optical methods and of modifyingoptical methods is in principle set by the diffraction limit (Abbe'slimit) at the respective wave length of the relevant optical signal.

Thus, in all known methods of creating a permanent structure with highspatial resolution by using an optical signal the diffraction barrier isthe natural lower limit of the resolution, for example in writing datainto an optical data storage and thus of the data density obtainable inthe data storage, and in microlithography. Up to know, it is necessaryto use light of shorter wavelength to create finer structures, like forexample in a photoresist. At present, deep-UV light is used; for thefuture, it is desired to use x-rays. One problem of this tendencytowards shorter wavelengths is that light of a wavelength of less than250 nm is hard to focus, and that the required lenses become more andmore expensive and inefficient.

In the field of fluorescence microscopy, however, methods are alreadyknown by which the spatial resolution in imaging a structure of a sampleis effectively enhanced beyond the diffraction limit by making use of anon-linear relationship between the sharpness of the definition of theeffective focal spot and the input intensity of an optical excitationsignal. Examples for these methods include multi-photon absorption in asample and generation of higher harmonics of input light. Saturation ofan optically induced transfer may also be used as a non-linearrelationship, like, for example, in case of stimulated emissiondepletion (STED) of the fluorescent state, and of ground state depletion(GSD).

In both of these known methods, which can in principle achieve amolecular resolution, a fluorescence dye, by which the structure ofinterest of a sample is marked, is transferred into an energy state,from which no fluorescence is (still) possible, everywhere where anoptical signal exceeds a characteristic threshold value, which will bereferred to as the saturation threshold value in this description. Ifthe spatially limited area, out of which a measurement signal is stillregistered, is defined by an intensity minimum of the optical signal,which has a zero intensity point and which is, for example, produced byinterference, the dimensions of the spatially limited area and thus theachieved spatial resolution are smaller than the diffraction limit. Thereason for this is that the spatially limited partial area out of whichthe measurement signal is registered is delimited with an increasinglevel of saturation of the depletion of the energy state involved influorescence. In the same way, the edge of a focal spot or stripebecomes steeper, which also results into an increased spatialresolution.

A particular STED method is known from WO 95/21393 A1. In this method, asample or a fluorescence dye, by which a structure of interest withinthe sample is marked, is excited for fluorescence by means of anexciting beam. The spatially limited area of the excitation, to whichthe diffraction limit normally applies, is then reduced in that it issuperimposed with an intensity minimum of an interference pattern of anoptical stimulation signal. Everywhere, where the optical stimulationsignal exceeds a saturation threshold value, the fluorescence dye is atleast essentially completely switched off by stimulated emission, i.e.it is brought down from the previously excited energy state. Theremaining spatially limited area out of which fluorescence light isstill spontaneously emitted afterwards only correspond to a reduced areaaround the center of the intensity minimum in which the stimulationsignal was not present or not present with a sufficient intensity.

From The Journal of Biological Chemistry, Vol. 275, No. 84, pages25879-25882 (2000) a protein is known which can increasingly be excitedfor fluorescence in a red range by means of green light, but whichlooses its fluorescence properties upon exposition to blue light. Thisprocess is reversible. It looks like that the green light switches theprotein to a state of conformation in which it has the fluorescenceproperty, and at the same times excites the fluorescence; whereas theblue light switches the protein into a state of conformation without thefluorescence property. The protein is a protein naturally occurring inthe sea anemone anemonia sulcata, the functions of which described heremay be purposefully enhanced by exchanging amino acids.

Further, it is known from Nature Vol. 388 pages 355-358 (1997) that thegreen fluorescent protein (GFP) and mutants thereof may be switchedbetween two states one of which differs from the other in a spectralaspect.

Both proteins mentioned here could be used as a fluorescence marker inliving cells.

From Nature, Vol. 420 pages 759-760 (2002) fluorescent molecules fromthe family of diarylethenes are known which may be deliberately switchedbetween a fluorescent and a non-fluorescent state. Both states arethermally stable so that the switching process can be accomplished atcomparatively low intensities. In this case, the switching process is aphotoisomerization. Such molecules can also be referred to asphotochromic.

There is a particular need for a method which enables surpassing thediffraction barrier in creating a permanent structure with high spatialresolution by using an optical signal. Further, there is a need of anapparatus suitable for carrying out such a method.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the invention provides a method of creating a permanentstructure with high spatial resolution, the method comprising the stepsof providing a substance, which may be modified by an optical signal, ina writing area; of applying the optical signal to the writing area insuch a way that a spatially limited partial area of the writing area ispurposefully omitted, the spatially limited partial area being a localintensity minimum of the optical signal, and the optical signal, outsideof the spatially limited partial area, being applied to the writing areain such a way that saturation is achieved in modifying the substancewith the optical signal; and of permanently adjusting different statesof the substance in the spatially limited partial area and of thesubstance in the partial areas of the writing area covered by theoptical signal.

In another aspect, the invention provides an apparatus having a writingarea adapted to be permanently modified by means of an optical signal,wherein the substance is selected from a group of substances which areadapted to be repeatedly transferred with the optical signal out of afirst state having first optical properties into a second state havingsecond optical properties differing from the first optical properties,which are adapted to be returned out of the second state into the firststate, and which are adapted to be permanently transferred by a writingsignal into an amended state out of the first state only.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention is further explained and described bymeans of preferred embodiments, details of which are shown in theattached drawings.

FIG. 1 symbolically shows two different states of a molecule which maybe used in an embodiment of the new method.

FIG. 2 shows an exemplary cyclic sequence of signals in the embodimentof the invention for which the molecule of FIG. 1 is suited; and

FIG. 3 schematically shows a device for carrying out the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the new method, the spatially limited partial area, which ispurposefully omitted with the optical signal and in which no or at leastessentially no modification of the substance by the optical signaloccurs, is a local intensity minimum of the optical signal.Additionally, the optical signal, outside of the spatially limitedpartial area, is applied to the writing area at such an intensity thatsaturation is achieved in modifying the substance with the opticalsignal. As a result the dimensions of the spatially limited partialarea, in which the substance is not modified by the optical signal, aresmaller than the diffraction barrier.

In the new method, the local intensity minimum of the optical signal isprovided by a light interference process. The term light interferenceprocess is to be interpreted very broadly here. It does not only coverthe superposition of two or even more beams of coherent light. Forexample, the interference effects occurring upon focusing a single beamof coherent light may also be used.

Saturation in modifying the substance with the optical signal isachieved in that the optical signal, outside of the spatially limitedpartial area, is applied to the writing area at an intensity above asaturation threshold value above which the substance is completely or atleast essentially completely modified by the optical signal. It shouldbe noted that, for surpassing the diffraction barrier, the saturationthreshold value is not only to be reached at the place of any intensitymaxima which are neighbouring the intensity minimum in the spatiallylimited partial area. Instead, the saturation threshold value has alsoto be exceeded in the direct neighbourhood of the local intensityminimum to effectively surpass the diffraction barrier. This can beachieved by increasing the intensity of the optical signal.

The new method can be used to create one-, two- or eventhree-dimensional structures in the writing area. A one-dimensionalstructure is a structure along a single line or a structured line; atwo-dimensional structure is a structure in a single plane or astructured plane; and a three-dimensional structure is a structurewithin a volume or a structured volume. It is clear that the writingarea has to be designed and provided with the substance in accordancewith the desired dimensionality of the structure. Preferably, thesubstance is homogenously or systematically distributed over the writingarea to care for uniform conditions in the whole writing area.

To the end of completely creating the structure in the writing area, itis intended to scan the writing area with the spatially limited partialarea purposefully omitted by the optical signal. As the structure may besimultaneously created in a plurality of distant points, i.e. in aplurality of spatially limited partial areas, the writing area may alsobe scanned with a plurality of plurality of spatially limited partialareas purposefully omitted by the optical signal at the same time. Inthis way, the total time needed for creating the respective structure isreduced.

As each spatially limited partial area omitted by the optical signal isan intensity minimum of an interference pattern, scanning can beaccomplished by movement of one intensity minimum or of a plurality ofinterference minima of the optical signal. This movement may beaccomplished by a phase shift of the interfering beams.

In the new method, the optical signal may directly be the writing signalby which the desired structure is created. To this end, the substance isto be selected from a group of substances which are adapted to bepermanently transferred out of a starting state into an amended state bythe optical signal. Then, the spatially limited partial areaspurposefully omitted by the optical signal constitute the desiredstructure having a spatial resolution surpassing the diffractionbarrier. Surpassing the diffraction barrier is not only achieved, whenthe created structure has dimensions below the diffraction barrier, butalso, when the transitions of the structure are sharper than normallydictated by the diffraction barrier. Particularly, data points, whichdisplay a particular sharpness and small dimensions whereas theirdistance is still limited by the diffraction barrier, can be writteninto an optical data storage in this particular embodiment of the newmethod, in which the optical signal is directly used as a writingsignal.

In a second general embodiment of the new method, even the distance ofsuch data points may be made smaller than the diffraction barrier. Tothis end, the substance is to be selected from a group of substanceswhich are adapted to be repeatedly transferred with the optical signalout of a first state having first properties into a second state havingsecond properties differing from the first properties, which are adaptedto be returned out of the second state into the first state, and whichare adapted to be permanently transferred by a writing signal into anamended state out of the first state only. I.e. the optical signal isnot yet the writing signal which is here separately applied to thewriting area. Instead, the optical signal is used to bring the substanceinto that state which is here denoted as the second state and out ofwhich no permanent amendment of the substance by the writing signaloccurs. The just temporary transfer of the substance out of its firststate into its second state by means of the optical signal is aprecondition for surpassing the diffraction barrier even with regard tothe distance of the details of the created structure in this embodimentof the new method. The structure is only amended by the writing signalin a partial area which has smaller dimensions than the diffractionbarrier. Whether further amendments are made in the surrounding of thispartial area, is not yet decided here. It is not essential that thefirst and second properties of the substance in its first and secondstate are “binary”, i.e. it is not necessary that they are each presentin the one state at 100% and in the other state at 0%. Instead, it issufficient, if the properties of the two states of the substance aredifferent with regard to the writing signal to such an extent that thewriting signal is clearly associated with the first state so thatessentially only the substance in its first state is permanently amendedby the writing signal.

In a preferred variant of the second embodiment of the new method, thewriting signal, which is applied in addition to the optical signal, alsois an optical signal. In this case, the first and second properties ofthe substance in its first and second state also include differentoptical properties, only the first properties of which support theoptical writing signal. The writing signal may also belong to the nonvisible part of the electromagnetic spectrum, for example to the farinfrared or to the microwave part. Electro-magnetic radiation having awavelength of less than 250 nm may also be used as an optical writingsignal. In any case, the advantage over the prior art remains that it isnot necessary to focus the writing signal to that partial area which isto be permanently amended within the writing area, because the partialareas to be permanently amended are spatially defined via the spatialdefinition of the second state of the substance by means of the opticalsignal. Thus, the writing signal may also be a non-electro-magneticsignal, like for example a thermal or chemical signal.

Substances having two different states with different properties whichare suitable for the new method may be selected from a sub-group ofsubstances in which the two states having the different properties aredifferent states of conformation of a molecule or of a group ofmolecules, or display different chemical bonds. The substances may alsobe selected from a sub-group of substances which are adapted to betransferred between the two states by photoisomerization orphotocyclization. Correspondingly, the optical signal may, in thesubstance, cause a rearrangement of bonds or atom groups, a cis-transisomerization, a cyclization reaction, a protonation or de-protonation,a spinflip, a change in orientation of molecules or molecule groups,and/or an electron transfer and/or an energy transfer betweeninterconnected molecules or molecule sub-units.

One big advantage of the new method is that the two states with thefirst and the second properties of several suitable substances have alife time which is several times longer than the energy states typicallyinvolved in fluorescence of a fluorescence dye. Further, the intensitieswhich are necessary for achieving the saturation of a change ofconfirmation are comparatively small. Changes of state in which thestarting state and/or the end state have a comparatively long life time(of more than 100 ns) may be effected with comparatively smallintensities of the optical signal. The required intensities become lowerwith the life times of the states becoming longer.

Preferably, such substances are used in the second embodiment of the newmethod which may be transferred out of the second into the first stateby means of a switching signal. By means of the other switching signal,the transfer of the substance with the optical signal into the secondstate can purposefully be reversed. The switching signal may be anoptical switching signal. It may, however, also be an electric orthermal signal, or a signal belonging to the non-optical part of theelectromagnetic spectrum. Further, it is possible, that the substancespontaneously returns into the first state, i.e. thermally driven atroom temperature. For example, it is known that molecules which undergoa photo-induced cis-trans-isomerization can simply thermally return totheir first state. By means of the switching signal, however, whichpurposefully returns the substance to the first state, the method maynormally be accelerated or at least be more precisely controlled.

To the end of avoiding undesired interactions between the differentsignals in the second embodiment of the new method, it is preferred ifthe permanent transfer of the substance into the amended state by thewriting signal may be reversed neither by the optical signal nor by theswitching signal.

The switching signal is applied to the writing area prior to opticalsignal, or, if the successful transfer of the substance into the secondstate by means of the optical signal is not essentially affected byswitching signal, at the same time as the optical signal. Particularlyit is not required to limit the switching signal to the spatiallylimited partial areas of the writing area in which the structure ispresently created. In the new method, the spatial limitation in creatingthe structure is provided by the optical signal.

The writing signal which also needs not to be restricted to thespatially limited partial areas of the writing area to be amended isapplied to the writing area after or at the same time as the opticalsignal. In case of a simultaneous application, it has again to be caredfor that no mutual disturbance must occur.

Although, as mentioned previously, the signals may overlap, theunderstanding of the second embodiment of the new method is enhancedupon considering the following sequences of signals which are cyclicallyrepeated. The substance in the writing area is in its first state. Inpartial areas of the writing area the substance is transferred into itssecond state by means of the optical signal. Doing this, the spatiallylimited partial area in which the substance is to be permanently amendedis omitted, and thus the substance within the spatially limited area isstill in its first state. Next, the substance is amended by means of thewriting signal to permanently get into its amended state within thespatially limited partial area. After this, the substance in the writingarea is returned to its first state. This may be done by means of theswitching signal. Afterwards, the cycle begins again but at anotherpoint of the writing area. In case of an only weakly localized writingsignal, the optical signal transferring the substance into its secondstate in which it is not sensitive for the writing signal has also tocover large areas of the writing area. This is not necessary with a morelocalized writing signal. The point in time at which the single signalsare present is defined by certain intensities of the signals beingreached. Thus, the signals may also be periodically modulated over thetime to realize the cyclic sequence of the signals.

The substance, for example, may be selected from the group of proteins.This group particularly includes the known proteins asCP (asFP595) andT70A/A148S/S165V which have two conformational states with differentoptical properties, and also the green fluorescent protein (GFP) andmutants derived thereof.

The permanent transfer of the substance into its amended state may bereversible or irreversible. If it is reversible, reversion should beeffected neither by the switching signal nor by any other signal used inthe original amendment. Instead, a further signal having totally otherproperties should be required for reversion of the amendment.

If the amended state of the substance into which it is permanentlytransferred according to the new method is an amended optical propertyof a group including absorption, diffraction and polarization, or anamended luminescence of a group including fluorescence, phosphorescence,electro-luminescence and chemo-luminescence, the created structure maybe read out by means of a probe beam.

Upon making full use of the opportunities of the present invention, datamay be written according to the new method into an optical data storageat a particularly high data density which is no longer delimited by thediffraction barrier. Similarly, micro and nano structures may be writtenor created with a spatial resolution surpassing the diffraction barrier.

The new apparatus according to the invention can be used forimplementing the second embodiment of the new method, and it isparticularly suited as an optical data storage.

The attached Figures which are discussed in the following areparticularly related to the second embodiment of the new method.

FIG. 1 shows structure formulas and energy states of a molecule whichcan be in two different states A and B. Out of state A, which is alsodenoted as the first state in the preceding description and the attachedclaims, the molecule may be permanently transferred into an amendedstate which is not depicted here by means of a writing signal 3. Thispermanent amendment of the substance is not possible out of state B,which is also denoted as the second state in the preceding descriptionand the attached claims. Particularly, the writing signal here transfersthe molecule within its state A out of an energetic ground state 1 intoan energetic excited state 2 out of which it permanently gets into theamended state not depicted here. The states A and B are two isomers (cisand trans) of a molecule which may be transferred out of its state Ainto its state B by photoisomerization caused by an optical signal 4,and out of state B back into state A also by means of an opticalswitching signal 5. In state B, the writing signal 3 does not resultinto a permanent amendment to the substance, as the excited energeticstate 2 which is at a higher energy level here is not reached.

FIG. 2 shows a preferred cyclic sequence of the signals, i.e. of theoptical signal 4, of the switching signal 5 and of the writing signal 3.Besides the states A and B the permanently amended state C of thepresent substance is also indicated here in parts c) to e) of FIG. 2.The sequence shown in the parts of FIG. 2 is: a) The switching signal 4switches the substance into its writable state A. b) The optical signal5 having at least one local intensity minimum 9 is applied to thewriting area 7, and switches the substance out of its state A into itsstate B everywhere outside the intensity minimum 9. Because of thesaturation of the switch process, the spatially limited partial area inwhich the substance still remains in its state A is reduced todimensions which are only dependent on the level of saturation and ofthe original steepness and width of the intensity minimum. c) Thewriting signal 3 transfers the substance being in state A but not instate B permanently into state C. d) The switching signal 4 switches thesubstance which has not been transferred into state C back into state A.e) The optical signal 5 is applied again, the zero intensity point 16 ofthe at least one intensity minimum 9 being positioned at another pointof the writing area 7.

FIG. 3 schematically shows a suitable device for carrying out theinvention. Optical beams 10 of the optical signal 5 are deformed bymeans of a wave front modulator 12 in such a way that they form aninterference pattern having an intensity minimum 9 with a zero intensitypoint 16 in the writing area 7 after passing a dichroic mirror 13 and alens 14. The optical signal saturates the transition 6 from state A tostate B so that only a sub-diffraction area of substance in state Aremains along the coordinate X depicted here. The writing signal 3 whichis applied to the writing area 7 via the dichroic mirror 13 and the lens14 transfers the substance being in state A permanently into the amendedstate C.

Many variations and modifications may be made to the preferredembodiments of the invention without departing substantially from thespirit and principles of the invention. All such modifications andvariations are intended to be included herein within the scope of thepresent invention, as defined by the following claims.

1. A method of creating a permanent structure with high spatialresolution, the method comprising the steps of: providing a substance,which may be modified by an optical signal, in a writing area; applyingthe optical signal to the writing area in such a way that a spatiallylimited partial area of the writing area is purposefully omitted, thespatially limited partial area being a local intensity minimum of theoptical signal, and the optical signal, outside of the spatially limitedpartial area, being applied to the writing area in such a way thatsaturation is achieved in modifying the substance with the opticalsignal; and permanently adjusting different states of the substance inthe spatially limited partial area and of the substance in the partialareas of the writing area covered by the optical signal.
 2. The methodof claim 1, wherein the local intensity minimum of the optical signalhas a zero intensity point.
 3. The method of claim 2, wherein the localintensity minimum of the optical signal is provided by an interferenceof light.
 4. The method of claim 1, wherein the optical signal, outsideof the spatially limited partial area, being applied to the writing areaat an intensity above a saturation threshold value above which thesubstance is essentially completely modified by the optical signal. 5.The method of claim 1, wherein a one-dimensional structure is created inthe writing area by means of permanently adjusting different states ofthe substance in the spatially limited partial area and in the partialareas of the writing area covered by the optical signal.
 6. The methodof claim 1, wherein a two-dimensional structure is created in thewriting area by means of permanently adjusting different states of thesubstance in the spatially limited partial area and in the partial areasof the writing area covered by the optical signal.
 7. The method ofclaim 1, wherein a three-dimensional structure is created in the writingarea by means of permanently adjusting different states of the substancein the spatially limited partial area and in the partial areas of thewriting area covered by the optical signal.
 8. The method of claim 1,wherein, in the step of providing, the substance is homogenouslydistributed over the writing area.
 9. The method of claim 1, wherein, inthe step of providing, the substance is systematically distributed overthe writing area.
 10. The method of claim 1, wherein the writing area isscanned with the partially limited area purposefully omitted by theoptical signal.
 11. The method of claim 10, wherein the writing area isscanned with a plurality of partially limited areas purposefully omittedby the optical signal at the same time.
 12. The method of claim 1,wherein the substance is selected from a group of substances which areadapted to be permanently transferred out of a starting state into anamended state by the optical signal.
 13. The method of claim 1, whereinthe substance is selected from a group of substances which are adaptedto be repeatedly transferred with the optical signal out of a firststate having first properties into a second state having secondproperties differing from the first properties, which are adapted to bereturned out of the second state into the first state, and which areadapted to be permanently transferred by a writing signal into anamended state out of the first state only.
 14. The method of claim 13,wherein the writing signal is an optical writing signal.
 15. The methodof claim 14, wherein the substance is selected from a sub-group ofsubstances in which the two states having the different properties aredifferent states of conformation of a molecule or of a group ofmolecules, or display different chemical bonds.
 16. The method of claim14, wherein the substance is selected from a sub-group of substanceswhich are adapted to be transferred between the two states by means ofphotoisomerization or photocylization.
 17. The method of claim 14,wherein the substance is selected from a sub-group of substances whichare adapted to be transferred out of the second state into the firststate by means of a switching signal.
 18. The method of claim 17,wherein the switching signal is an optical switching signal.
 19. Themethod of claim 17, wherein the permanent transfer of the substance intothe amended state by the writing signal is reversed neither by theoptical signal nor by the switching signal.
 20. The method of claim 17,wherein the switching signal is applied to the writing area essentiallyprior to optical signal.
 21. The method of claim 17, wherein theswitching signal is applied to the writing area essentially at the sametime as the optical signal.
 22. The method of claim 14, wherein thewriting signal is applied to partial areas of the writing area coveredby the optical signal and to the spatially limited area omitted by theoptical signal.
 23. The method of claim 14, wherein the writing signalis applied to the writing area essentially after the optical signal. 24.The method of claim 14, wherein the writing signal is applied to thewriting area essentially at the same time as the optical signal.
 25. Themethod of claim 14, wherein the substance is selected from a sub-groupof substances including proteins.
 26. The method of claim 1, wherein thedifferent states of the substance comprise different optical properties.27. The method of claim 26, wherein the different states of thesubstance comprise different optical properties selected from a groupincluding different absorption, diffraction and polarization properties.28. The method of claim 1, wherein the different states of the substancecomprise different luminescence properties selected from a groupincluding different fluorescence, phosphorescence, electro-luminescenceand chemo-luminescence properties.
 29. The method of claim 1, whereinthe writing area is the writing area of an optical data storage.
 30. Themethod of claim 1, wherein the structure is a lithographic structure.31. A method of creating a permanent structure with high spatialresolution, the method comprising the steps of: selecting a substancefrom a group of substances which are adapted to be repeatedlytransferred with an optical signal out of a first state having firstoptical properties into a second state having second optical propertiesdiffering from the first optical properties, which are adapted to bereturned out of the second state into the first state, and which areadapted to be permanently transferred by a writing signal into anamended state out of the first state only; providing the substance in awriting area; applying the optical signal to the writing area in such away that a spatially limited partial area of the writing area ispurposefully omitted, the spatially limited partial area being a localintensity minimum of the optical signal, and the optical signal, outsideof the spatially limited partial area, being applied to the writing areain such a way that saturation is achieved in modifying the substancewith the optical signal; and applying the writing to the writing area topermanently transfer the substance within the spatially limited partialarea into the amended state.
 32. An apparatus having a writing areaadapted to be permanently modified by means of an optical signal,wherein the substance is selected from a group of substances which areadapted to be repeatedly transferred with the optical signal out of afirst state having first optical properties into a second state havingsecond optical properties differing from the first optical properties,which are adapted to be returned out of the second state into the firststate, and which are adapted to be permanently transferred by a writingsignal into an amended state out of the first state only.
 33. Theapparatus of claim 32, wherein the writing area is the writing area ofan optical data storage.